CNC or automatic surface grinder question

Oct 27, 2008 4 Replies

Caution on topic post........ (I asked on CNCzone too, this may get lost in all the politics here.)



On a CNC or automatic surface grinder when should the wheel advance (crossfeed) over the work, when the table is fully right or fully left. I would think it would be correct to advance the wheel when the table is left so as the table comes back to the right you are making a conventional cut as opposed to climb grinding.



I have my "new" Brown and Sharpe Techmaster in place and need to start using it, while using it over the next few weeks/months I need to correct the programming in the PLC. It was converted to an Allen Bradley SLC 500 plc from its original Modicon.



The programming in it is just enough to make it go back and forth and advance the wheel in incremental mode only. The other crossfeed settings do nothing and the crossfeed STOP button only causes the light to light and does not stop anything at all.



The first item on my list is does it crossfeed at the correct end of stroke?



Thank You, Randy



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Go with constant infeed, so the wheel is actually cutting on the face. Make it infeed all the time while it's traversing. If you infeed on one end only or only at each end your actually plunge grinding which will be hotter and will wear the wheel more.

Its been a while but IIRC usually you will setup so that you can feed at either as well as at *both* ends--also, you can setup to auto-reverse the crossfeed direction at both ends of the Y stroke which ( when given a relatively high cross feedrate ) produces sort of a "random crosshatch" pattern.

But the most important thing to do here ( unless the unit already has automatic dressing ) is you wanna firmly mount your diamond at a position that is outside of your normal travel range ( crash avoidance ) and then LEAVE IT THERE--now, after you've writen a dedicated program for your dressing routine, you have pretty much eliminated the guesswork that's involved with trying to accurately reach final size via the "cut and measure" methods....IOW, once you know what the diamond height is, you now can easily compensate after each dressing so as to accurately ascertain the actual distance from the freshly dressed wheel down to the the chuck surface....

HTH

The Techmaster is not CNC, it is semi-automatic controlled Via a PLC. I do have the ability to auto-reverse the crossfeed or let it stop. Machine has an over head dresser (not automatic) which I have not yet got working, it's stuck. DRO is in the plans.

I could change the PLC programming to crossfeed at both ends, this is how my old mechanical grinder advanced.

Since I'm basically acting as a machine builder here, I could add a switch on the front panel to choose between Xfeed at one end or both. However this will be my first ever Allen Bradley PLC programming attempt so this might take awhile.

How does a true CNC surface grinder handle the cross feed? Is it up to the programmer or is there a canned cycle?

Thank You, Randy

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Randy wrote in news: snipped-for-privacy@4ax.com:

It's up to the programmer. Most of the ones I've seen can feed like Vinny described. The cross feed infeeds, continuously while the table is traversing.

You can also put multiple parts on the table and grind at different heights, etc.

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